1. Field of the Invention
The present invention relates to variable operation intake valve controlling apparatus and method for an internal combustion engine in which a cam operational angle variable mechanism which is capable of controlling a cam operational angle (also called, a working angle) of the intake valve to continuously expand (widen) and shrink (narrow) the intake valve and a cam phase angle variable mechanism which is capable of displacing a lift center angle of the intake valve in either an advance angle direction or a retardation angle direction.
2. Description of the Related Art
A Japanese Patent Application First Publication No. 2001-280167 published on Oct. 10, 2001 exemplifies a previously proposed variable operation intake valve controlling apparatus.
In order to achieve a valve lift characteristic which is optimum for the present engine driving condition, a cam operational angle (which will be described later) of the intake valve of the engine is enabled to be controlled so as to be continuously expanded (widened) or shrunk (narrowed) or a phase variable mechanism a cam phase of a lift center angle of the intake valve is retarded or advanced are combined to form a variable operation engine valve mechanism. In addition, another Japanese Patent Application First Publication No. 2001-263104 published on Sep. 26, 2001 exemplifies another previously proposed variable operation engine valve controlling apparatus. In the latter Japanese Patent Application First Publication, a technique of controlling an intake valve closure timing and an exhaust valve closure timing so as to achieve a target value of a rate of a residual gas quantity within each cylinder using electromagnetic operation intake valve and electromagnetic operation exhaust valve.